Conventional police batons are in the form of a rigid, one-piece, elongate, inextensible structure of solid cross section. It is the purpose of this invention to provide a two-piece structure comprising a rigid, elongate, tubular structure and a rigid, elongate shaft of solid cross section disposed in the tube and movable therein relative to the tube from a contracted position confined within the tube to an expanded position projecting from the tube. This invention allows the police officer to carry the police baton easier when it is in the collapsed position. Also, when the officer opens the expandable baton, it gives the officer an "element of surprise" not provided by other batons.